1. Technical Field
This invention describes methods of contraception and prophylaxis against sexually transmitted diseases (STDs), including acquired immunodeficiency syndrome (AIDS), and compositions and devices for use in such methods.
2. Background Information
There is an urgent need, worldwide, for improved contraceptives, especially male contraceptives. There is also an urgent need, worldwide, for improved prophylactic methods for preventing the spread of STDs. Vaccines could be highly valuable for meeting these needs and substantial efforts are being made to develop vaccines that will stimulate the body to synthesize its own antibodies against sperm and against STD pathogens. However, no contraceptive vaccine is yet available, and for some STDs, including AIDS, there is considerable doubt that a vaccine can ever be developed--infected individuals develop high titers of anti-HIV antibodies but this immunity to HIV does not stop the fatal course of AIDS.
In the absence of vaccines, the most effective methods now available for preventing both pregnancy and STDs are the condom, and the topical spermicidal contraceptives--foams, jellies, suppositories, and sponges. Condoms are both contraceptive and prophylactic since they create a mechanical barrier that prevents sperm as well as STD pathogens in the ejaculate from contacting the sexual partner. Many topical contraceptives are also both contraceptive and prophylactic since they use detergents for their active (spermicidal) ingredient, usually the nonionic detergent nonoxynol-9. Detergents not only kill (lyse) sperm, they also kill many pathogenic bacteria, protozoa, and viruses. Unfortunately, detergents also injure epithelial cells, and many people cannot use topical contraceptives because the detergents cause too much irritation, especially to the urethra. Also, detergents are only active for a short time after being applied to a mucus epithelium: contraceptive suppositories start to become unreliable about 45 minutes after being inserted in the vagina because detergents become inactive after solubilizing oily molecules. Detergents are also absorbed into the body through mucus epithelia.
If used properly, condoms as well as topical contraceptives are highly effective in preventing pregnancy and disease. However, numerous studies have shown that the reliability of both these methods is limited almost entirely by "user failure". That is, the condom is not put on in time, or not at all, or the suppository is inserted too early, too late, or not at all. Such "user failure" is usually due to the bother of using these prophylactic contraceptive methods--they require actions and interruptions inconsistent with sexual behavior. Moreover, topically applied detergents strongly inhibit most forms of oral sex, and condoms are often disliked by men because they interfere with foreplay, reduce the sensations of intercourse, and are a bother to remove, and dispose, postcoitally.
Thus there is a need, both for men and for women, for prophylactic contraceptives that are more reliable because they are less of a bother to use and require procedures more consistent with sexual activity. The most convenient and popular methods of contraception now available (the "pill", and intrauterine devices, IUDs,) provide little or no protection against STDs. Most users of these methods also need, and desire, protection against STDs, especially with the advent of AIDS.
Finally, many couples desire to conceive, and/or for religious or moral reasons do not wish to contracept, but they still need to protect each other from exchanging STDs. About one fourth of all infertile couples in the United States are infertile as a result of STDs, especially Chlamydia, an STD that is often asymptomatic and readily passes back and forth between two partners. There is thus a significant need for methods that are prophylactic against STDs but are not contraceptive. No such methods are now available.